Backlight assembly and display apparatus

ABSTRACT

The present disclosure provides a backlight assembly and a display apparatus comprising the backlight assembly. The backlight assembly includes a light source and at least one light-absorbing substance. The light source is configured to emit a white light, the white light comprising at least two primary color lights. The at least one light-absorbing substance is disposed at a light-out side of the light source and is configured to absorb light in at least one overlapping portion between spectra of two of the at least two primary color lights in the white light.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Chinese Patent ApplicationNo. 201610108769.4 filed on Feb. 26, 2016, the disclosure of which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to the field of displaytechnologies, and more specifically to a backlight assembly and adisplay apparatus.

BACKGROUND

As a type of flat-panel display apparatus, LCDs (liquid crystaldisplays) have increasingly been applied in the field ofhigh-performance display due to their advantages such as small size, lowpower consumption, low radiation, and low manufacturing cost. However,LCD is a passive light-emitting display device, a backlight unit, orbacklight assembly, is typically needed to provide a light source to thedevice to display images.

SUMMARY

In one aspect, the present disclosure provides a backlight assembly. Thebacklight assembly includes a light source and at least onelight-absorbing substance. The light source is configured to emit awhite light, the white light comprising at least two primary colorlights. The at least one light-absorbing substance is disposed at alight-out side of the light source and configured to absorb light in atleast one overlapping portion between spectra of two of the at least twoprimary color lights in the white light.

In some embodiments of the backlight assembly, the light source includesa light-emitting chip and a phosphor layer. The phosphor layer isconfigured such that the light-emitting chip emits a first primary colorlight, the first primary color light becoming the white light afterpassing through the phosphor layer.

The first primary color light can be a blue light, and the phosphorlayer can comprise at least one phosphor, which is configured to formthe white light upon activation by the blue light emitted by thelight-emitting chip. The phosphor layer can comprise a yellow phosphor,or can comprise a red phosphor and a green phosphor.

In some embodiments of the backlight assembly, the at least onelight-absorbing substance can comprise at least one dye.

In some of the above embodiments, the at least one dye can include acis-isomerized indigo, which can have absorption peaks of about 480 nmand 540 nm.

In others of the above embodiments, the at least one dye can include atrans-isomerized indigo, which can have an absorption peak of about 580nm.

The at least one light-absorbing substance can exist in a variety ofdifferent components in the backlight assembly.

In a first embodiment, the at least one light-absorbing substance canexist in at least one of a light guide plate and at least one opticalfilm in an optical film group of the backlight assembly.

In a second embodiment, the at least one light-absorbing substance canexist in at least one light-absorbing film, which can be disposed on alight-in side, or on a light-out side, of a light guide plate of thebacklight assembly. For example, the at least one light-absorbing filmcan be disposed between the light guide plate and an optical film groupof the backlight assembly.

In a third embodiment, the at least one light-absorbing substance canexist in at least one of a diffusive plate and at least one optical filmin an optical film group of the backlight assembly.

In a fourth embodiment, the at least one light-absorbing substance canexist in at least one light-absorbing film, which can be disposed on alight-in side, or on a light-out side, of a diffusive plate of thebacklight assembly. For example, the at least one light-absorbing filmcan be disposed on a light-out side of the diffusive plate of thebacklight assembly, and the at least one light-absorbing film caninclude two light-absorbing films, each comprising one differentlight-absorbing substance.

The backlight assembly can further comprise an optical film group. Theoptical film group can include an upper prism plate and a lower prismplate, and the two light-absorbing films are disposed respectivelybetween the upper prism plate and the lower prism plate, and between thediffusive plate and the lower prism plate.

In another aspect, a display apparatus is also provided in the presentdisclosure. The display apparatus can include a backlight assemblyaccording to any of the embodiments as mentioned above.

Other embodiments may become apparent in light of the above embodimentsas described above.

BRIEF DESCRIPTION OF THE DRAWINGS

To more clearly illustrate some of the embodiments, the following is abrief description of the drawings. The drawings in the followingdescriptions are only illustrative of some embodiments. For those ofordinary skill in the art, other drawings of other embodiments canbecome apparent based on these drawings.

FIG. 1 is a superimposed view of the lights and the color filter layerof a conventional backlight assembly;

FIG. 2 is a schematic view of color gamut of a conventional backlightassembly;

FIG. 3 is a spectrum diagram of the white light emitted by aconventional light source;

FIG. 4 is a spectrum diagram of the white light emitted by the lightsource after passing through a light-absorbing substance-containing partof a backlight assembly according to some embodiments of the presentdisclosure;

FIG. 5 is a schematic view of a backlight assembly according to a firstembodiment of the present disclosure;

FIG. 6 is a schematic view of a backlight assembly according to a secondembodiment of the present disclosure;

FIG. 7 is a schematic view of a backlight assembly according to a thirdembodiment of the present disclosure;

FIG. 8 is a schematic view of a backlight assembly according to a fourthembodiment of the present disclosure;

FIG. 9 is a schematic view of a backlight assembly according to a fifthembodiment of the present disclosure;

FIG. 10 is a schematic view of the absorption spectrum of the firstlight-absorbing film according to some embodiments of the presentdisclosure;

FIG. 11 is a schematic view of the absorption spectrum of the secondlight-absorbing film according to some embodiments of the presentdisclosure;

FIG. 12 is a schematic view of a display apparatus according to a firstembodiment of the present disclosure;

FIG. 13 is a schematic view of a display apparatus according to a secondembodiment of the present disclosure.

DETAILED DESCRIPTION

In the following, with reference to the drawings of various embodimentsdisclosed herein, the technical solutions of the embodiments of thedisclosure will be described in a clear and fully understandable way. Itis obvious that the described embodiments are merely a portion but notall of the embodiments of the disclosure. Based on the describedembodiments of the disclosure, those ordinarily skilled in the art canobtain other embodiment(s), which come(s) within the scope sought forprotection by the disclosure.

The light source in the backlight assembly typically comes from thewhite light generated when the blue light-emitting chip activates theyellow phosphor. The spectrum of the light source in a conventionalbacklight assembly is shown as the waveform I in FIG. 1. The half-wavewidth of the blue light in the spectrum of the light source isrelatively small, and the half-wave widths of the red light and thegreen light are relatively large.

The liquid crystal display device typically also comprises a colorfilter layer, configured to optically filter the backlight provided bythe backlight assembly. The light transmission spectrum of the colorfilter layer is as shown as the waveform II in FIG. 1.

As shown in the waveform III in FIG. 1, when the backlight havingwaveform I passes through the color filter layer that has a transmissionspectrum of waveform II, the blue light (B) and the green light (G) havea relatively large overlapping portion of the spectrum at position x,and the green light (G) and the red light (R) have a relatively largeoverlapping portion of the spectrum at position y.

As a result, the color purity of the emitted green light (G) and redlight (R) is relatively low, i.e., the purity of the three primarycolors emitted by the backlight assembly is relatively low. In addition,the color coordinate (a) of the green light (G) is pulled closer to thatof the blue light (B) and the red light (R), and the color coordinate(b) of the red light (R) is similarly pulled closer to that of the greenlight (G), as shown in FIG. 2. Consequently, the area of the triangleoab formed by the color coordinates of the red, green and blue lightafter color filtering is relatively small, and the color gamut of thedisplay apparatus employing the backlight assembly as such is relativelysmall.

To solve the above issues associated with conventional backlightassemblies, the present disclosure provides a backlight assembly.

The backlight assembly includes a light source and at least onelight-absorbing substance. The light source emits a white light, and theat least one light-absorbing substance is disposed at a light-out sideof the light source and configured to absorb light in at least oneoverlapping portion between spectra of two primary color lights in thewhite light.

The light source of the backlight assembly can include a light-emittingchip and a phosphor layer, and the light-emitting chip can emit a firstprimary color light, which becomes a white light after passing throughthe phosphor layer. The white light includes a first primary colorlight, a second primary color light, and a third primary color light.

The at least one light-absorbing substance can exist in at least onepart of the backlight assembly at the light-out side of the light sourceand is configured to absorb light of certain wavelengths in at least oneoverlapping portion between spectra of two primary color lights in thewhite light emitted by the light source.

The first primary color light, the second primary color light, and thethird primary color light can be red light, green light, or blue light.Embodiments of the present disclosure will be illustrated in detail withan example where the first primary color light is blue light, the secondprimary color light and the third primary color light are red light andgreen light respectively.

In some embodiments of the present disclosure, the light-emitting chipemits a blue light, the second primary color light is a red light, andthe third primary color light is a green light. As such, in embodimentsof the present disclosure, the light-emitting chip can be a chip thatemits a blue light, the phosphor layer can comprise at least onephosphor that can be mixed with the blue light emitted by thelight-emitting chip to form a white light.

Specifically, the phosphor layer can include one single color phosphor,or can include a mixture of multiple phosphors. For example, thephosphor layer can comprise only yellow phosphor, and the blue lightemitted by the light-emitting chip becomes a white light after passingthrough the yellow phosphor layer. The phosphor layer can also comprisea mixture of multiple phosphors. For example, it can comprise redphosphor and green phosphor, or it can comprise yellow phosphor and redphosphor, etc. The present disclosure will not list all examples herein.

The at least one light-absorbing substance can absorb light of certainwavelengths in the white light emitted by the light source, i.e., afterthe light source emits the white light, the white light is output afterpassing through a part of the backlight assembly containing the at leastone light-absorbing substance.

Specifically, the at least one light-absorbing substance can absorb onlythe light in a first overlapping portion between spectra of the firstprimary color light and the second primary color light, or can absorbonly the light in a second overlapping portion between spectra of thesecond primary color light and the third primary color light, or canabsorb both the light of the first overlapping portion between spectraof the first primary color light and the second primary color light andthe light in the second overlapping portion between spectra of thesecond primary color light and the third primary color light at the sametime.

Furthermore, when only the light in the first overlapping portionbetween spectra of the first primary color light and the second primarycolor light or the light in the second overlapping portion betweenspectra of the second primary color light and the third primary colorlight is absorbed, there can exist only one light-absorbing substance.When both the light in the first overlapping portion between spectra ofthe first primary color light and the second primary color light and thelight in the second overlapping portion between spectra of the secondprimary color light and the third primary color light are absorbed atthe same time, multiple light-absorbing substances can be present at thesame time.

Embodiments of the present disclosure are illustrated with an examplewhere the light-emitting chip emits a blue light, the second primarycolor light is a red light, the third primary color light is a greenlight, and the at least one light-absorbing substance can absorb boththe light in the first overlapping portion between spectra of the firstprimary color light and the second primary color light and the light inthe second overlapping portion between spectra of the second primarycolor light and the third primary color light at the same time.

Because the light-emitting chip emits blue light, as shown in FIG. 3,the half-wave width of the blue light (B) in the white light emitted bythe light source is relatively small, and the half-wave width of the redlight (R) and green light (G) are relatively large. The light of certainwavelengths in an overlapping portion between spectra of the red lightand the green light in the white light emitted by the light source isabsorbed by the at least one light-absorbing substance. The light ofcertain wavelengths in an overlapping portion between spectra of theblue light and the green light in the white light emitted by the lightsource is also absorbed by the at least one light-absorbing substance.Compared with that prior to absorption, the overlapping portion of thehalf-wave widths of the red light (R) and the green light (G) isreduced, and the overlapping portion of the half-wave widths of the bluelight (B) and the green light (G) is also reduced. As illustrated inFIG. 4, the half-wave widths of the blue light (B), the red light (R)and the green light (G) are all relatively small.

When the white light of the backlight assembly as disclosed hereinpasses through the color filter layer that has a transmission spectrumof waveform II in FIG. 1, the overlapping portion of the spectra of theblue light (B) and the green light (G) (shown at position x for aconventional display assembly in FIG. 1), and the overlapping portion ofthe spectra of the green light (G) and the red light (R) (shown atposition y for a conventional display assembly in FIG. 1) also becomesmaller.

On the one hand, the color purity of the green light (G) and the redlight (R) is improved, i.e., the purity of the three primary colorsemitted by the backlight assembly is relatively high.

On the other hand, as shown in FIG. 2, the color coordinate (a′) of thegreen light (G), the color coordinate (b′) of the red light (R) and thecolor coordinate (o) of the blue light (B) are all far away from thecenter, and the area of the triangle oa′b′ formed by the colorcoordinates of the red light, the green light, and the blue light aftercolor filtering is relatively large; as such, the color gamut of thedisplay apparatus employing the backlight assembly is relatively large.

The backlight assembly can further comprise other parts. For example, abacklight assembly typically comprises parts such as a frame, a backplate and reflective film. These parts are not related to the inventiveaspects of the present disclosure, and thus description of these partsis skipped herein.

The present disclosure provides a backlight assembly, whose light sourcecomprises a light-emitting chip and a phosphor layer. The light-emittingchip emits a first primary color light, which becomes white light afterpassing through the phosphor layer. The white light comprises a firstprimary color light, a second primary color light, and a third primarycolor light. Because the light-emitting chip emits the first primarycolor light, the half-wave width of the first primary color light in thebacklight emitted by the backlight assembly is relatively small, thehalf-wave widths of the second primary color light and third primarycolor light are relatively large.

The backlight assembly further comprises at least one light-absorbingsubstance, configured to absorb the light in the overlapping portionbetween spectra of the second primary color light and the third primarycolor light. As such, the overlapping portion between the spectra of thesecond primary color light and the third primary color light is reduced.As a consequence, the half-wave widths of the first primary color light,the second primary color light, and the third primary color light in thewhite light emitted by the backlight assembly become all relativelysmall, the color purity of the three primary colors emitted by thebacklight assembly is increased, and the color gamut of the displayapparatus employing the backlight assembly is thus improved.

In some embodiments, the at least one light-absorbing substance isfurther configured to absorb the light in the overlapping portionbetween spectra of the first primary color light and the second primarycolor light in the white light emitted by the light source to furtherimprove the purity of the first primary color light in the backlightassembly and increase the range of color gamut.

It should be appreciated that the at least one light-absorbing substancecan be arranged at various positions in the backlight assembly andarranged in various ways. Herein the various ways mean employingexisting parts of, or adding new parts to, the backlight assembly.

In some preferred embodiments, at least one optical film can be dopedwith at least one light-absorbing substance in an optical film group inthe backlight assembly, and/or a light guide plate can be doped with atleast one light-absorbing substance in the backlight assembly.

FIG. 5 illustrates an example with a side-in backlight assembly. Thebacklight assembly 10 comprises a light source 2, a reflective plate 1,a light guide plate 3, and an optical film group 4. The light source 2is disposed at the side of the light guide plate 3; and the light guideplate 3 is doped with at least one light-absorbing substance. When thewhite light emitted by the light source 2 passes through the light guideplate 3, the at least one light-absorbing substance in the light guideplate 3 can absorb light in at least one overlapping portion of thespectra of two primary color lights in the white light.

Alternatively, as shown in FIG. 6, the backlight assembly 10 comprises alight source 2, a reflective plate 1, a light guide plate 3, and anoptical film group 4. The light source 2 is disposed at the side of thelight guide plate 3, i.e., it is a side-in backlight assembly. Alight-absorbing film 7, doped with at least one light-absorbingsubstance, is disposed at the light-in side or light-out side of thelight guide plate 3 of the backlight assembly 10. FIG. 6 illustrates anexample where the light-absorbing film 7 is configured at the light-outside of the light guide plate 3.

Alternatively, in a preferred embodiment, the at least onelight-absorbing substance can be doped in at least one optical film inthe optical film group of the backlight assembly, and/or in thediffusive plate of the backlight assembly.

As shown in FIG. 7, the backlight assembly 10 is a straight-downbacklight assembly, which comprises a light source 2, a reflective plate1, a diffusive plate 5, and an optical film group 4. The light source 2is disposed under the diffusive plate 5; and the diffusive plate 5 isdoped with at least one light-absorbing substance. When the white lightemitted by the light source 2 passes through the diffusive plate 5, theat least one light-absorbing substance in the diffusive plate 5 canabsorb light in at least one overlapping portion of the spectra of twoprimary color lights in the white light.

Alternatively, in a preferred embodiment as shown in FIG. 8, thebacklight assembly 10 comprises a light source 2, a reflective plate 1,a diffusive plate 5, and an optical film group 4. The light source 2 isdisposed under the diffusive plate 5, i.e., it is a straight-downbacklight assembly. The light-absorbing film 7 is doped with at leastone light-absorbing substance; the light absorbing film 7 is configuredat the light-in or light-out side of the diffusive plate of thebacklight assembly. FIG. 8 illustrates an example where thelight-absorbing film 7 is configured at the light-out side of thediffusive plate 7.

In some embodiments, as shown in FIGS. 5-8, the backlight assembly 10further comprises an optical film group 4, which typically alsocomprises an upper prism plate, and a lower prism plate etc. The presentdisclosure is illustrated with an example where the optical film group 4comprises an upper prism plate 41 and a lower prism plate 42. The atleast one light-absorbing substance can be present in at least one ofthe optical film in the optical film group 4 of the backlight assembly10. As such, when the light emitted by the light source 2 passes throughthe optical film group 4, the at least one light-absorbing substance inthe optical film can absorb light in at least one overlapping portion ofthe spectra of two primary color lights in the white light.

Alternatively, the at least one light-absorbing substance can exist in alight-absorbing film or a light-absorbing film set, disposed over thesurface of at least one optical film in the optical film group of thebacklight assembly. That is, the optical film group further comprises alight-absorbing film. When the light emitted by the light source passesthrough the optical film group, the at least one light-absorbingsubstance in the light-absorbing film can absorb light in at least oneoverlapping portion of the spectra of two primary color lights in thewhite light.

In some embodiments, as shown in FIG. 9, the backlight assembly 10comprises a light source 2, a reflective plate 1, a diffusive plate 5,an optical film group 4, and a light-absorbing film set 7. Thelight-absorbing film set 7 comprises a first light-absorbing film 71 anda second light-absorbing film 72, wherein the first light-absorbing film71 is disposed between an upper prism plate 41 and a lower prism plate42; the second light-absorbing film 72 is disposed at the light-out sideof the diffusive plate 5. The first light-absorbing film 71 is dopedwith a first light-absorbing substance, and the second light-absorbingfilm 72 is doped with a second light-absorbing substance.

In some preferred embodiments of the present disclosure, the firstlight-absorbing substance in the first light-absorbing film 71 and thesecond light-absorbing substance in the second light-absorbing film 72can absorb different wavelength of light, i.e., the firstlight-absorbing film and the second light-absorbing film are configuredto respectively absorb the light of certain wavelengths of the secondprimary color light and the third primary color light. For example, thefirst light-absorbing film is configured to absorb the light of certainwavelengths from the third primary color light, whereas the secondlight-absorbing film is configured to absorb the light of certainwavelengths from the second primary color light.

For example, FIG. 10 is a schematic view of the absorption spectrum of afirst light-absorbing film doped with a first light-absorbing substanceaccording to some embodiments of the present disclosure. The absorptionpeak of the first light-absorbing film is about 260 nm, 480 nm, and 540nm, and as such, the first light-absorbing film can absorb theoverlapping portion (˜490 nm-510 nm) of the spectrum of the blue lightand the spectrum of the green light.

FIG. 11 is a schematic view of the absorption spectrum of a secondlight-absorbing film doped with a second light-absorbing substanceaccording to some embodiments of the present disclosure. The absorptionpeak of the second light-absorbing film is about 260 nm and 580 nm, andas such, the second light-absorbing film can absorb the overlappingportion (˜560 nm-600 nm) of the spectrum of the green light and thespectrum of the red light.

In some preferred embodiments, the light-absorbing substance is a dye.Specifically, the light-absorbing substance can comprise indigo, whereinthe first light-absorbing substance and the second light-absorbingsubstance can respectively be indigo derivatives.

For example, the first light-absorbing substance can be a cis-isomerizedindigo, and FIG. 10 illustrates the absorption spectrum of the firstlight-absorbing film doped with the first light-absorbing substance. Thesecond light-absorbing substance can be a trans-isomerized indigo, andFIG. 11 illustrates the absorption spectrum of the secondlight-absorbing substance doped with the second light-absorbingsubstance. The light-absorbing substance is not limited to the abovelisted types: for example, it can be other types of indigo derivatives,embodiments of the present disclosure illustrate with theabove-described examples.

It should be appreciated that, when both the light in a firstoverlapping portion between spectra of the first primary color light andthe second primary color light and the light in a second overlappingportion between spectra of the second primary color light and the thirdprimary color light are absorbed at the same time, a part of thebacklight assembly, such as a light guide plate, can comprise differenttypes of light-absorbing substances at the same time.

The present disclosure further provides a display apparatus, comprisingany one of the backlight assemblies as described above.

For example, as shown in FIG. 12, a display apparatus 100 can comprise abacklight assembly 10 and a display panel 11. The display panel 11 isdisposed at the light-out side of the backlight assembly 10. Thebacklight assembly 10 comprises a light source 2, a reflective plate 1,a light guide plate 3, an optical film group 4, a light-absorbing film7, and a substrate 9, wherein the light source 2 is disposed at the sideof the light guide plate 3, and as such, the backlight assembly is aside-in backlight assembly.

Alternatively, as shown in FIG. 13, another display apparatus 100provided by embodiments of the present disclosure comprises a backlightassembly 10 and a display panel 11, wherein the display panel 11 isdisposed at the light-out side of the backlight assembly 10. Thebacklight assembly 10 comprises a light source 2, a reflective plate 1,a diffusive plate 5, an optical film group 4, a light-absorbing film 7and a substrate 9. The light source 2 is disposed under the diffusionplate 5, and as such, the backlight assembly 10 is a straight-downbacklight assembly.

Although specific embodiments have been described above in detail, thedescription is merely for purposes of illustration. It should beappreciated, therefore, that many aspects described above are notintended as required or essential elements unless explicitly statedotherwise. Various modifications of, and equivalent acts correspondingto, the disclosed aspects of the exemplary embodiments, in addition tothose described above, can be made by a person of ordinary skill in theart, having the benefit of the present disclosure, without departingfrom the spirit and scope of the disclosure defined in the followingclaims, the scope of which is to be accorded the broadest interpretationso as to encompass such modifications and equivalent structures.

The invention claimed is:
 1. A backlight assembly, comprising: a lightsource; and at least one light-absorbing substance; wherein: the lightsource is configured to emit a white light, the white light comprising afirst, a second, and a third primary color lights respectivelycorresponding to blue, red, and green; the at least one light-absorbingsubstance is disposed at a light-out side of the light source andconfigured to absorb light in at least one overlapping portion betweenspectra of two of the at least two primary color lights in the whitelight; the at least one light-absorbing substance comprises a firstsubstance with absorption peaks of about 480 nm and 540 nm, comprisingat least a cis-isomerized indigo dye and a second substance, with anabsorption peak of 580 nm, comprising a trans-isomerized indigo dye tothereby reduce half-wave widths of the second and third primary colorlights, such that half-wave widths of the first, second, and thirdprimary color lights become all are reduced to be in a range of 20 nm100 nm to thereby improve color purity of the backlight assembly.
 2. Thebacklight assembly of claim 1, wherein the light source comprises alight-emitting chip and a phosphor layer, configured such that thelight-emitting chip emits the first primary color light, the firstprimary color light becoming the white light after passing through thephosphor layer.
 3. The backlight assembly of claim 2, wherein thephosphor layer comprises at least one phosphor, configured to form thewhite light upon activation by blue light emitted by the light-emittingchip.
 4. The backlight assembly of claim 3, wherein the phosphor layercomprises a yellow phosphor, or comprises a red phosphor and a greenphosphor.
 5. The backlight assembly of claim 1, wherein the at least onelight-absorbing substance exists in at least one of: a light guideplate; or at least one optical film in an optical film group of thebacklight assembly.
 6. The backlight assembly of claim 1, wherein the atleast one light-absorbing substance exists in at least onelight-absorbing film, disposed on a light-in side, or on a light-outside, of a light guide plate of the backlight assembly.
 7. The backlightassembly of claim 6, wherein the at least one light-absorbing film isdisposed between the light guide plate and an optical film group of thebacklight assembly.
 8. The backlight assembly of claim 1, wherein the atleast one light-absorbing substance exists in at least one of: adiffusive plate; or at least one optical film in an optical film groupof the backlight assembly.
 9. The backlight assembly of claim 1, whereinthe at least one light-absorbing substance exists in at least onelight-absorbing film, disposed on a light-in side, or on a light-outside, of a diffusive plate of the backlight assembly.
 10. The backlightassembly of claim 9, wherein the at least one light-absorbing film isdisposed on a light-out side of the diffusive plate of the backlightassembly, and the at least one light-absorbing film comprises twolight-absorbing films, each comprising one different light-absorbingsubstance.
 11. The backlight assembly of claim 10, further comprising anoptical film group, the optical film group comprising an upper prismplate and a lower prism plate, wherein the two light-absorbing films aredisposed respectively between the upper prism plate and the lower prismplate, and between the diffusive plate and the lower prism plate.
 12. Adisplay apparatus, comprising a backlight assembly according to claim 1.13. The display apparatus of claim 12, wherein the display apparatus hasimproved color gamut resulting from improved uniformity of the half-wavewidths of the first, second, and third primary color lights.